For a 2.6 kernel its in Device Drivers -> Character Devices (not the most obvious place I'd agree) Just enable the DRM part, but don't compile in the Radeon driver, this comes in the xfree-drm package.

Can someone explain to me which DRM Radeon driver is best... The CVS one (does anyone use this? if so how do you install it?) the x.org version (does x.org have DRM built in?) or the XFree 4.3 version installed by portage using emerge xfree-drm?

Presumably these will enable 2D acceleration and 3D acceleration (?), but are they good enough for example to work in Blender or another OpenGL apps or games? Is the 2D desktop as snappy as an x86 system?

Lots of questions I know, i would be eternally grateful if you could answer at least some of them though

I'm using x.org on 2.6.3-benh2 with the kernel DRM drivers and it's working great. I think I'm getting around 550fps with glxgears (sorry, I can't be more exact cause I'm posting from OS X at the moment).

I did notice however, that x.org installs a new folder in /usr/src with source for the drm drivers. I haven't tried these yet though.